Process for the preparation of compounds having -CH2-CHF-groups

ABSTRACT

Compounds each having a —CH 2 —CHF— group and a number of carbon atoms of 4 or above are prepared by hydrogenating a compound having a —CCl═CF— group and a number of carbon atoms of 4 or above in the presence of a noble metal catalyst in a liquid or gas phase. The compound having a —CCl═CF— group and a number of carbon atoms of 4 or above is preferably a C 4 -C 10  alicyclic one, and can be prepared by reacting a compound having a —CCl═CCl— group and a number of carbon atoms of 4 or above with a fluorinating agent.

TECHNICAL FIELD

This invention relates to a process for preparing a compound having atleast 4 carbon atoms and a —CH₂—CHF— group which is useful as adetergent or a solvent.

BACKGROUND ART

In processes for washing various materials in an industrial scale, asolvent composition predominantly comprised of a freon having goodincombustibility, low-toxicity and good stability were heretofore widelyused. However, freon destroys An ozone layer and invites global warming,and thus, regulations on suppression of the use of freon have beenestablished and the production thereof has been absolutely prohibitedall over the world.

Under these circumstances, extensive researches have been made fordeveloping various alternatives for freon. One type of the alternativesfor freon is hydrofluorocarbons having no chlorine atom which is atypical example of the ozone layer-destroying factors. It is well knownthat hydrofluorocarbons have no chlorine atom and are incombustible andstable. It is also known that hydrofluorocarbons exhibit satisfactorywashing performance when they are used either alone or in combinationwith an organic solvent.

It is expected that hydrofluorocarbon compounds having a —CH₂—CHF— groupare new fluorine-containing materials as hydrofluorocarbons having nochlorine atom. The hydrofluorocarbon compounds having a —CH₂—CHF— groupdo not destroy the ozone layer and have a short life in the air, andthus, cause the global warming only to a minimum extent. In addition,the hydrofluorocarbon compounds are capable of dissolving contaminantsto an appropriate extent, do not affect plastic articles, and exhibitgood stability against heat and chemicals and good incombustibility.

As for a process for preparing a chain-like hydrofluorocarbon compoundhaving a —CH₂—CHF— group, only a process for preparing ahydrofluorocarbon compound having 3 carbon atoms is known. For example,a process for preparing CF₃CH₂CHF₂ by hydrogenating CF₃CH═CF₂ in thepresence of a hydrogenation catalyst is described in Japanese UnexaminedPatent Publication (hereinafter abbreviated to “JP-A”) No. H8-2594775. Aprocess for preparing CF₃CH₂CHF₂ by hydrogenating CF₃CCl═CF₂ in thepresence of a reducing catalyst is described in Japanese UnexaminedPatent Publication (hereinafter abbreviated to “JP-A”) No. H8-337542.These processes have problems such that three hydrogen atoms must beintroduced in the molecule in two stages and the synthesis of a rawmaterial, CF₃CCl═CF₂ is troublesome and costly. Therefore, an improvedprocess is desired.

It is known that, in a process for preparing1,1,2,2,3,3,4,5-octafluorocyolopentane by allowing perfluorocyclopenteneto react with hydrogen in the presence of a noble metal catalyst suchas, for example, palladium, 1,1,2,2,3,3,4-heptafluorocyclopentane, whichis an alicyclic hydrocarbon compound having a —CH₂—CHF— group and atleast 4 carbon atoms, is produced as a side reaction product (Journal ofAmerican Chemical Society, p548, 1968). But, there is no description ofseparating 1,1,2,2,3,3,4-heptafluorocyclopentane from the reactionproduct. In fact, 1,1,2,2,3,3,4-heptafluorocyclopentane and1,1,2,2,3,3,4,5-octafluorocyolopentane have boiling points which arevery close to each other, and therefore, the former is impossible toseparate from the latter by distillation.

A process for producing a compound having at least 4 carbon atoms and a—CH₂—CHF— group in an industrial scale has not heretofore been proposed.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide a process forproducing a compound having at least 4 carbon atoms and a —CH₂—CHF—group with a high purity in an industrially advantageous manner.

As a result of extensive researches for achieving the object, thepresent inventors have found a process whereby the objecthydrofluorocarbon compound can be produced at a high purity by utilizingthe difference between a chlorine atom and a fluorine atom In reactivityof replacement with hydrogen.

Further, the present inventors have completed an industriallyadvantageous process for producing the object hydrofluorocarbon compoundinvolving a scheme of reactions which includes a reaction for producingthe starting compound need in the above-process.

In one aspect of the present invention, there is provided a process forpreparing a compound having at least 4 carbon atoms and represented bythe. following formula (3), characterized in that a compound having atleast 4 carbon atoms and represented by the following formula (1) ishydrogenated in the presence of a noble metal catalyst in the liquidphase or the vapor phase;

R¹—C¹Cl═C²F—R²  (1)

wherein R¹ is a fluorine atom or an alkyl group having 1 to 8 carbonatoms which may be fluorinated, and R² is a hydrogen atom, a fluorineatom or an alkyl group having 1 to 8 carbon atoms which may befluorinated, provided that at least one of R¹ and R² is an alkyl grouphaving 1 to 8 carbon atoms which may be fluorinated, and that the sum ofcarbon atoms in R¹ and R² is at least two, and R¹ and R² may formtogether a divalent hydrocarbon group having 2 to 8 carbon atomsrepresented by the formula —R¹—R²—, in which the entirety or a part ofthe hydrogen atoms in the hydrocarbon group of formula —R¹—R²— may befluorinated, and which forms together with C¹ and C² an alicycliccompound;

R³—C³H₂—C⁴HF—R⁴  (3)

wherein R³ and R⁴ are the same as R¹ and R² in formula (1),respectively.

In another aspect of the present invention, there is provided a processfor preparing a compound having at least 4 carbon atoms and representedby the formula (3), characterized in that a compound having at least 4carbon atoms and represented by the following formula (4):

R⁵—C⁵Cl═C⁶Cl—R⁶  (4)

wherein R⁵ and R⁶ are the same as R¹ and R² in the formula (1),respectively, is allowed to react with a fluorinating agent to give thecompound having at least 4 carbon atoms and represented by the formula(1); and then the compound of formula (1) is hydrogenated in thepresence of a noble metal catalyst.

BEST MODE FOR CARRYING OUT THE INVENTION

The process of the present invention is concerned with conversion of acompound having at least 4 carbon atoms and a —CCl═CF— group into acompound having at least 4 carbon atoms and a —CH₂—CHF— group byhydrogenating the former compound in the presence of a noble metalcatalyst.

The compound used as the starting material in the process of the presentinvention is a chain-like compound or preferably an alicyclic compound,which is represented by the following formula (1). The number of carbonatoms in the main chain of the chain-like compound of formula (1) or thecyclic structure of the alicyclic compound of formula (1).

R¹—C¹Cl═C²F—R²  (1)

wherein R¹ is a fluorine atom or an alkyl group having 1 to 8 carbonatoms which may be fluorinated, and R² is a hydrogen atom, a fluorineatom or an alkyl group having 1 to 8 carbon atoms. A part or theentirety of the alkyl group having 1 to 8 carbon atoms may befluorinated. However, at least one of R¹ and R² is an alkyl group having1 to 8 carbon atoms which may be fluorinated, and that the sum of carbonatoms in R¹ and R² is at least two. R¹ and R² may form together adivalent hydrocarbon group having 2 to 8 carbon atoms represented by theformula —R¹—R²—, in which the entirety or a part of the hydrogen atomsin the hydrocarbon group of formula —R¹—R²— may be fluorinated, andwhich forms together with C¹ and C² an alicyclic compound.

Substituents R¹ and R² are selected, as mentioned above, from a hydrogenatom, a fluorine atom and an unsubstituted alkyl group having 1 to 8carbon atoms and an alkyl group having 1 to 8 carbon atoms, a part orthe entirety of which is fluorinated, provided that R¹ is not a hydrogenatom. Of these, a fluorine atom and a perfluoroalkyl group having 1 to 8carbon atoms are preferable.

As specific examples of the perfluoroalkyl group having 1 to 8 carbonatoms, there can be mentioned a perfluoromethyl group, a perfluoroethylgroup, a perfluoro-n-propyl group. a perfluoroisopropyl group, aperfluoro-n-butyl group, a perfluoro-tert-butyl group, perfluoropentylgroups, perfluorohexyl groups, perfluoroheptyl groups and perfluorooctylgroups.

R¹ and R² in formula (1) may form together a divalent hydrocarbon grouphaving 2 to 8 carbon atoms represented by the formula —R¹—R²—, whichforms together with C¹ and C² an alicyclic compound represented by thefollowing formula (2).

The divalent hydrocarbon group —R¹—R²— has 2 to 8 carbon atoms,preferably 2 to 4 carbon atoms. A part or the entirety of the hydrogenatoms in the divalent hydrocarbon group may be fluorinated. Preferablythe entirety of the hydrogen atoms is fluorinated.

As specific examples of a perfuoroalkylene group, i.e., a divalenthydrocarbon group of formula —R¹—R²— having 2 to 8 carbon atoms, theentirety of which is fluorinated, there can be mentioned aperfluoroethylene group, a perfluoro-n-propylene group, aperfluoroisopropylene group, a perfluoro-n-butylene group, aperfluoro-tert-butylene group, perfluoropentylene groups,perfluorohexylene groups, perfluoroheptylene groups andperfluorooctylene groups.

As examples of the alicyclic compound of formula (2), which is formedfrom C¹ and C² and the divalent hydrocarbon group of formula —R¹—R²— inthe formula (1), there can be mentioned a cyclobutene compound, acyclopentene compound, a cyclohexene compound, a cycloheptene compoundand a cyclohexene compound. Of these, a cyclobutene compound, acyclopentene compound and a cyclohexene compound are preferable. Acyclopentene compound is especially preferable.

The compound of formula (1) includes chain-like chlorofluoroalkenecompounds and alicyclic chlorofluoroalkene compounds. As specificexamples of the chain-like chlorofluoroalkene compound, there can bementioned 1-chloroheptafluorobutene, 2-chloroheptafluorobutene,1-chlorononafluoropentene, 2-chlorononafluoropentene,3-chlorononafluoro-2-pentene, 1-chloroundecafluorohexene,2-chloroundecafluorohexene and 3-chloroundecafluoro-2-hexene. Asspecific examples of the alicyclic chlorofluoroalkene compound, therecan be mentioned 1-chloropentafluorocyclobutene,1-chloroheptafluorocyclopentene, 1-chlorononafluorocyclohexene,1-chloro-5-trifluoromethyloctafluorocyclohexene and1-chloroundecafluorocycloheptene. Of these, 1-chlorononafluoropentene,2-chlorononafluoropentene, 3-chlorononafluoro-2-pentene and1-chloroheptafluorocyclopentene are preferable.1-chloroheptafluorocyclopentene is most preferable.

The hydrogenation reaction will now be described.

Hydrogen used for the hydrogenation reaction is gaseous. Hydrogen ispreferably used in an amount more than equimolar to the compound offormula (1). More specifically hydrogen La used preferably in an amountof at least two mols, more preferably 2 to 50 mole, per mol of thecompound of formula (1).

The noble metal catalyst used is a noble metal or a noble metalcompound, Preferably the noble metal catalyst is used in a formsupported by a carrier. As specific examples of the noble metal, therecan be mentioned palladium, rhodium, ruthenium, rhenium and platinum. Ofthese, palladium, rhodium and ruthenium are preferable. Palladium ismost preferable. As specific examples of the noble metal compound, therecan be mentioned salts such as palladium acetate, palladium sulfate andpalladium nitrate, and halides such as palladium chloride.

The noble metal catalyst may be comprised of either a single metal or analloy comprising at least two kinds of metals, i.e., a bimetal catalyst,The alloy is preferably an alloy predominantly comprised of palladium.

Kind, shape and size of the carrier used for supporting the noble metalcatalyst are not particularly limited. The kinds of carrier include, forexample, active carbon, silica gel, titania, zirconia and hydrogenfluoride-treated products thereof. The shape of carrier includes, forexample, a powder, a sphere and a particle form such as a pellet. Theparticle may be either a molded particle or a pulverized product of aparticulate form. Preferably the shape is a powder for the liquid phasereaction, and a particle form for the vapor phase reaction. The amountof the noble metal supported on the carrier is usually in the range of0.05 to 20% by weight, and preferably, 0.1 to 20% by weight for apowdery carrier, and 0.1 to 10% by weight for a particulate carrier.More preferably a powdery catalyst having 0.1 to 10% by weight of anoble metal supported on a powdery carrier is used for the liquid phasereaction, and a particulate catalyst having 0.5 to 7% by weight of anoble metal supported on a particulate carrier are used.

The hydrogenation reaction is carried out In the liquid phase or thevapor phase. A solvent may be optionally used in the liquid phasereaction, and a diluent may be optionally used in the vapor phasereaction. The vapor phase reaction can be carried out, for example, by afixed bed vapor phase reaction procedure or a fluidized bed vapor phasereaction procedure.

The solvent used in the liquid phase reaction is not particularlylimited, and includes, for example, aliphatic hydrocarbons, aromatichydrocarbons, hydrofluorocarbons, alcohols, ethers, ketones, esters andwater.

The aliphatic hydrocarbons usually have 4 to 15 carbon atoms, and, asspecific examples thereof, there can be mentioned n-butane, n-pentane,methylpentane, n-hexane, cyolopentane and cyclohexane.

As a specific example of the aromatic hydrocarbons, there can bementioned trifluoromethylbenzene.

As specific examples of the hydrofluorocarbons, there can be mentionedpentafluoroethane, pentafluoropropane, hexafluorobutane anddecafluoropentane.

The alcohols usually have 1 to 10 carbon atoms, preferably 1 to 6 carbonatoms, and, as specific examples of the alcohols, there can be mentionedmethanol, ethanol, propanol, butanol and cyclopentanol.

The ethers usually have 4 to 10 carbon atoms, preferably 4 to 6 carbonatoms, and, as specific examples of the ethers, there can be mentioneddiethyl ether, diisopropyl ether and ethylene glycol dimethyl ether.

The ketones usually have 3 to 10 carbon atoms, preferably 3 to 8 carbonatoms, and, as specific examples of the ketones, there can be mentionedacetone, methyl ethyl ketone, methyl isopropyl ketone, methyl butylketone and cyclopentanone.

The esters usually have 4 to 10 carbon atoms, preferably 3 to 8 carbonatoms, and, as specific examples of the esters, there can be mentionedethyl acetate, butyl acetate, propyl acetate, methyl propionate, methylbutyrate and methyl valerate.

These solvents may be used either alone or as a combination of at leasttwo thereof. The amount of the solvent is not particularly limited, butit is usually in the range of 0 to 80 parts by weight, preferably 0 to50 parts by weight, based on 100 parts by weight of the compound havinga —CCl═CF— group.

The diluent used in the vapor phase reaction is inert to thehydrogenation reaction, and includes nitrogen gas, rare gas, hydrocarbongas and hydrofluorocarbon gas. As specific examples of the diluent,there can be mentioned rare gas such as argon gas and helium gas;hydrocarbon gas such as methane gas, ethane gas, propane gas and butanegas; and hydrofluorocarbon gas such as pentafluoroethane,pentafluoropropane, hexafluorobutane and decafluoropentane.

These diluents may be used either alone or as a combination of at leasttwo there of, The amount of the diluent is not particularly limited, butit is usually in the range of 0 to 500 parts by weight, preferably 0 to200 parts by weight, based on 100 parts by weight of the compound havinga —CCl═CF— group.

The pressure in the hydrogenation reaction system is usually in therange of about normal pressure to about 50 kgf/cm², and preferablynormal pressure to 20 kgf/cm². The reaction temperature is usually inthe range of about normal temperature to about 350° C., and preferablyabout normal temperature to about 200° C., If desired, the reactionsystem can be stirred or shaken.

The hydrogenation reaction of the present invention can be carried outby a batchwise manner or a continuous manner wherein a raw material iscontinuously fed into a reactor and a reaction product is continuouslywithdrawn from the reactor.

The reaction vessel used is a pressure vessel for a batchwise reactionmanner and one or more reactors connected in series, for example,cascade reactors, for a continuous reaction manner. The material of thereaction vessel is preferably, for example, stainless steel. Thereaction vessel made of stainless steel is preferably subjected toconditioning by a treatment with nitric acid prior to the use thereof.

In the hydrogenation reaction, acidic ingredients such as hydrogenchloride gas are produced as by-products. It is preferable to remove theacidic ingredients by absorption or neutralization during the reaction.The removal can be carried out by incorporating an additive into thereaction system. The additive includes, for example, hydroxides, oxides,weak acid salts and organic acid salts of an alkali metal or an alkalineearth metal. As specific examples of the additive, there can bementioned soda lime, quick lime, alkali metal carbonate and alkali metalacetate. These additives may be used either alone or as a combination ofat least two thereof. The additive is usually used In an amount of atleast equivalent to the compound of formula (1).

After completion of the hydrogenation reaction, if desired, an additiveIs incorporated in the reaction mixture to remove acidic ingredients byadsorption or neutralization, thereafter the objective compound isseparated by a conventional purification procedure such as distillation.

The objective compound produced by the process of the present inventionis a compound having at least 4 carbon atoms and represented by thefollowing formula (3), which is a chain-like compound or an alicycliccompound, An alicyclic compound is preferable as the compound of formula(3). The number of carbon atoms contained in the main chain of thechain-like compound or in the cyclic structure of the alicyclic compoundis usually in the range of 4 to 10, preferably 4 to 6 and mostpreferably 5

R³—C³H₂—C⁴HF—R⁴  (3)

wherein R³ and R⁴ are the same as R¹ and R² in the above-mentionedformula (1), respectively. As being the same as in the formula (1), oneof R³ and R⁴ is an alkyl group having 1 to 8 carbon atoms which may befluorinated; the sum of carbon atoms in R³ and R⁴ is at least two; andR³ and R⁴ may form together a divalent hydrocarbon group having 2 to 8carbon atoms represented by the formula —R³—R⁴—, which forms togetherwith C³ and C⁴ an alicyclic compound.

As specific examples of the perfluoroalkyl group having 1 to 8 carbonatoms, which is a preferable example of R³ and R₄, there can bementioned those which are recited as for R¹ and R² in formula (1). Asspecific examples of the perfluoroalkylene group having 2 to 8 carbonatoms, represented by the formula —R³—R⁴—, there can be mentioned thosewhich are recited as for —R¹—R²—.

The compound of formula (3) having at least 4 carbon atoms includeschain-like compounds and alicyclic compounds. As specific examples ofthe chain-like compound, there can be mentioned1,1,1,2,4,4,4-heptafluoro-n-butane,1,1,1,2,2,3,5,5,5-nonafluoro-n-pentene,1,1,1,2,2,4,5,5,5-nonafluoro-n-pentene,1,1,1,2,2,3,3,4,6,6,6-undecafluoro-n-hexane,1,1,1,2,2,3,3,5,6,6,6-undecafluoro-n-hexane and1,1,1,2,2,4,5,5,6,6,6-undecafluoro-n-hexane. As specific examples of thealicyclic compound, there can be mentioned1,1,2,2,3-pentafluorocyclobutane, 1,1,2,2,3,3,4-heptafluorocyclopentaneand 1,1,2,2,3,3,4,4,5-nonafluoro-cyclohexane. Of these,1,1,1,2,2,3,5,5,5-nonafluoro-n-pentene and1,1,2,2,3,3,4-heptafluorocyclopentane are preferable.1,1,2,2,3,3,4-heptafluorocyclopentane is most preferable.

The process for preparing the compound having at least 4 carbon atoms,represented by the formula (1), which is used as a starting raw materialfor the hydrogenation reaction, is not particularly limited, but,preferably the compound of formula (1) is prepared by allowing acompound having at least 4 carbon atoms, represented by the followingformula (4). to react with a fluorinating agent. In this reaction, oneof the two chlorine atoms in the group —C⁵Cl═C⁵Cl— of the compound offormula (4) is substituted by a fluorine atom.

The compound represented by the following formula (4), used in thepresent invention, is a chain-like compound or an alicyclic compound. Analicyclic compound is preferable. The number of carbon atoms in the mainchain or cyclic structure of the compound of formula (4) are usually inthe range of 4 to 10, preferably 4 to 6 and most preferably 5.

R⁵—C⁵Cl═C⁵Cl—R⁵  (4)

In the formula (4), R⁵ and R⁶ are the same as R¹ and R², respectively,in the formula (1). As being the same as R¹ and R² in the formula (1).one of R⁵ and R⁶ is an alkyl group having 1 to 8 carbon atoms which maybe fluorinated; the sum of carbon atoms in R⁵ and R⁶ is at least two,and R⁵ and R⁶ may form together a divalent hydrocarbon group having 2 to8 carbon atoms represented by the formula —R⁵—R⁶—, which forms togetherwith C⁵ and C⁶ an alicyclic compound.

As specific examples of the perfluoroalkyl group having 1 to 8 carbonatoms, which is a preferable example of R⁵ and R⁶, there can bementioned those which are recited as for R¹ and R² in formula (1). Asspecific examples of the perfluoroalkylene group having 2 to 8 carbonatoms, represented by the formula —R⁵—R⁶—, there can be mentioned thosewhich are recited as for —R¹—R²— in the formula (1).

As specific examples of the chain-like compound of formula (4), therecan be mentioned 1,2-dichlorohexafluoro-1-butene,2,3-dichlorohexafluoro2-butene, 1,2-dichlorooctafluoro-1-pentene,2,3-dichlorooctafluoro-2-pentene and 1,2-dichlorodecafluoro-1-hexene. Asspecific examples of the alicyclic compound of formula (4), there can bementioned1,2-dichloroteterafluorocyclobutene-1,1,2-dichlorohexafluorocyclopentene-1and 1,2-dichlorooctafluoracyclohexene-1, Of these,1,2-dichlorooctafluoro-1-pentene, 2,3-dlchlorooctafluoro-2-pentene and1,2-dichlorohexafluorocyclopentene-1 are preferable.1,2-dichlorohexafluorocyclopentene-1 is most preferable.

The fluorinating agent used is not particularly limited, provided thatit is capable of releasing a fluorine ion. As examples of thefluorinating agent, there can be mentioned metal fluorides, aqueous oranhydrous hydrofluoric acid, associated products of hydrofluoric acidwith an amine or a quaternary ammonium salt, and an associated productof hydrofluoric acid with a polar solvent. Of these, metal fluorides arepreferable.

The metal fluorides include, for example, fluorides of an alkali metal,an alkaline earth metal and a transition metal. Of these, alkali metalfluorides are preferable. As specific examples of the alkali metalfluorides, sodium fluoride, potassium fluoride and lithium fluoride.Potassium fluoride is most preferable. These fluorinating agents may beused either alone or as a combination of at least two thereof.

The amount of the fluorinating agent is at least 0.5 mol per mol of thecompound having at least 4 carbon atoms of formula (4). However, inorder to prevent substitution of both of the two chlorine atoms in the—ClC═CCl— group, the amount of the fluorinating agent is preferably notlarger than 2 mols, more preferably in the range of 0.5 to 1.2 mole, permol of the compound of formula (4).

The fluorinating reaction may be carried out either in the liquid phaseor the vapor phase, When an alkali metal hydride is used, thefluorinating reaction Is usually carried out in the liquid phase undernormal pressure.

When the fluorinating reaction is carried out in the liquid phase, asolvent can be used, As the solvent, an aprotic polar solvent is usuallyused. As specific examples of the aprotic polar solvent, there can bementioned N-methylpyrrolidone, N,N-dimethylformamide,N,N-dimethylacetamide and N,N′-dimethylimidazolidinone. Of these,N-methylpyrrolidone and N,N-dimethylformamide are preferable. Thesesolvents may be used either alone or as a mixture of at least twothereof. If desired, these aprotic polar solvents may be used incombination with compatible aromatic hydrocarbon solvents such asbenzene, toluene, xylene and mesitylene.

The amount of the Solvent is not particularly limited, but is usually inthe range of 0 to 1,000 parts by weight based on 100 parts by weight ofthe compound of formula (4).

The reaction temperature in the liquid phase reaction is appropriatelychosen from the range of 20° C. to 200° C., preferably 50° C. to 150° C.and more preferably 80° C. to 130° C.

When the reaction is carried out in the liquid phase, the reaction ispreferably effected In a solvent having a metal fluoride dispersedtherein, by using a reaction vessel equipped with a distillation column.In this liquid phase reaction, it is preferable that only the objectivecompound is concentrated and separated at a high purity from the toppart of the distillation column, and simultaneously, the raw materialand intermediate reaction products are returned under reflux to thereaction vessel without discharge therefrom.

When the fluorinating reaction is carried out in the vapor phasereaction, a diluent can be used. As specific examples of the diluent,there can be mentioned solvents which are recited as examples of thesolvent used in the liquid phase reaction.

The reaction temperature in the vapor phase reaction is appropriatelychosen from the range of 100° C. to 500° C.

The fluorinating reaction can be carried out either in a batchwisemanner or a continuous manner wherein the raw material is continuouslyfed into a reaction vessel and the reaction product is continuouslywithdrawn from the reaction vessel.

When alkali metal fluorides such as potassium fluoride are used as afluorinating agent in the fluorinating reaction, alkali metal chloridessuch as potassium chloride are produced as by-products. Theseby-products are removed by filtration or washing with water, aftercompletion of the reaction.

In the case of the vapor phase reaction, unreacted fluorinating agent ispreferably removed by absorption or neutralization. When unreactedfluorinating agent is removed. an additive can be added in the reactionmixture, if desired. The additive used includes hydroxides, oxides, weakacid salts and organic acid salts of alkali metals and alkalineearthmetals As specific examples of the additive, there can be mentionedsoda lime, quicklime, alkali carbonate and alkali acetate. Theseadditives may be added either alone or de a combination of at least twothereof.

The amount of the additive used is usually at least one equivalent tothe compound of formula (4).

After completion of the reaction, the reaction product is purified by anordinary procedure such as distillation, or dried as it is, to give thecompound of formula (1).

The invention will now be specifically described by the followingexamples. In the examples, % is by weight.

EXAMPLE 1

Fluorination of Dichloroalkene

A glass flask equipped with a distillation column at the upper partthereof was charged with 1,2-dichlorohexafluorocyclopentene (50.10 g,0.205 mol), potassium fluoride (13.05 g, 0.225 mol) andN,N-dimethylformamide (50 ml), and the content was heated to 120° C.with stirring. When 0.3 hour elapsed from the commencement of heating,production of a distillate was begun. After completion of thedistillation, the pressure within the flask was reduced and the residuewas collected in a cooling trap. The distillate and the collectedresidue were combined together, and then neutralized and washed with anaqueous sodium bicarbonate solution. The analysis of the thus-obtainedproduct showed that the objectivecompound1-chloroheptafluorocyclopentene was obtained in a yield of79.1%,

Vapor Phase Hydrogenation of Chlorofluoroalkene

A pressure reaction vessel was charged with the thus-obtained1-chloroheptafluorocyolopentene (15 g, 65.6 m-mols), a 5%-palladiumcarbon catalyst (5% by weight), sodium acetate (10.9 g) and water (25.0ml). and the content was stirred under a hydrogen pressure of 10kgf/cm². After 24 hours elapsed, the reaction liquid was filtered toremove the catalyst, and the organic phase was separated and washed withwater. Unreacted materials were removed from the thus-obtained product.Analysis of the product showed that the objective compound1,1,2,2,3,3,4-heptafluorocyclopentane and a by-product1,1,2,2,3,3-heptafluorocyclopentane were obtained in a proportion of 50%and 40%, respectively. The product was fractionated to give1,1,2,2,3,3,4-heptafluorocyclopentane at a purity of 98%.1,1,2,2,3,3,4-heptafluorocyclopentane had a boiling point of 80° C./760mmHg, 1,1,2,2,3,3-heptafluorocyclopentane had a boiling point of 87°C./760 mmHg.

EXAMPLE 2

Liquid Phase Hydrogenation of Chlorofluoroalkene

By the same procedures as described in Example 1,1-chloroheptafluorocyclopentene was prepared and then hydrogenatedwherein sodium acetate and water were not used in the hydrogenation andthe hydrogenation reaction time was varied to 30 hours. All otherconditions remained the same. Unreacted materials were removed from thethus-obtained product. Analysis of the product showed that the objectivecompound1,1,2,2,3,3,4-heptafluorocyclopentane and a side reactionproduct 1,1,2,2,3,3-heptafluorocyclopentane were obtained in aproportion of 70% and 2%, respectively.

EXAMPLE 3

Fluorination of Dichloroalkene

A 500 ml glass flask equipped with a distillation column at the upperpart thereof was charged with 1,2-dichlorohexafluorocyclopentene (254 g,1.04 mole), potassium fluoride (66 g, 1.14 mols) andN,N-dilmethylformamide (150 ml), and the content was heated to 110° C.with stirring. When 0.5 hour elapsed from the commencement of heating,production of a distillate was begun. The reaction product was begun tobe drawn from the top of the distillation column at a reflux ratio of10:1 and collected in a receptacle which was immersed in an ice-waterand dry ice-acetone bath. While the drawing of the reaction product wascontinued, the heating temperature was gradually elevated, and, when thetemperature of the top of the distillation column reached the boilingpoint of N,N-dimethylformamide, the heating was stopped. Thus, 225 g ofa crude product was obtained. Analysis of the crude product by gaschromatography revealed that the contents of1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentane and1,2,3,3,4,4,5,5-octafluorocyclopentene were 98.8% and 1.2%,respectively.

Then the crude product was distilled by a fractionating column with atheoretical plate number of 8 to collect a fraction having a boilingpoint of 56° C./760 mmHg. Thus 197 g (yield; 89%) of1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene with a purity of 99.9%was obtained.

Vapor Phase Hydrogenation of Chlorofluoroalkene

The obtained 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene washydrogenated in the liquid phase by the same procedures as mentioned inExample 1. The results were similar to those obtained in Example 1.

EXAMPLE 4

Fluorination of Dichloroalkene

A 300 ml glass flask equipped with a distillation column at the upperpart thereof was charged with 1,2-dichlorohexafluorocyclopentene (104 g,0.42 mol), potassium fluoride (27 g, 0.47 mol), N,N-dimethylformamide(50 ml) and toluene (50 ml), and the content was heated to 95° C. withstirring. When 2.5 hours elapsed from the commencement of heating, adistillate was begun to appear. The reaction product was begun to bedrawn from the top of the distillation column at a reflux ratio of 10:1and collected in a receptacle which was immersed in an ice-water and dryice-acetone bath. While the drawing of the reaction product wascontinued, the heating temperature was gradually elevated, and, when thetemperature of the top of the distillation column reached the boilingpoint of toluene, the heating was stopped. Thus, 85 g of a crude productwas obtained. Analysis of the crude product by gas chromatographyrevealed that the contents of1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene,1,2,3,3,4,4,5,5-octafluorocyclopentene and1,2-dichlorohexafluorocyclopentene were 98.8%, 0.2% and 1.0%,respectively.

Vapor Phase Hydrogenation of Chlorofluoroalkene

The obtained 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene washydrogenated in the liquid phase by the same procedures as mentioned inExample 2. The results were similar to those obtained in Example 2.

EXAMPLE 5

Fluorination of Chlorofluoroalkene

An SUS 316 reaction tube having a diameter of ½ inch and a length of 15cm and equipped with an external electric oven was packed with 5 ml of apalladium catalyst (supplied by Nikki Kagaku K.K,.) comprising 0.5% byweight of palladium supported on alumina spheres. The catalyst-packedreaction tube was heated to 150° C. The heated reaction tube waspre-treated with hydrogen by flowing hydrogen gas through the tube at arate of 200 ml/min for 8 hours. Thereafter1-chloro-2,3,3,4,4,5,5-heptafluoro-cyclopentene was supplied at a rateof 0.1 ml/min to a vaporizer maintained at 100° C., and thehydrogenation was carried out for 30 hours. The thus-produced gaseousmixture was washed with water, and dried with calcium chloride, and thencollected in a glass trap cooled to −78° C. Analysis of the collectedproduct by gas chromatography revealed that the conversion of the rawmaterial was 99%, and the contents of1,1,2,2,3,3,4-heptafluorocyclopentene,1,3,3,4,4,5,5-heptafluoro-cyclopentene and1,1,2,2,3,3-hexafluorocyclopentane were 90%, 8.5% and 0.5%,respectively.

EXAMPLE 6

Fluorination of Chlorofluoroalkene

An SUS 316 reaction tube having a diameter of ½ inch and a length of 15cm and equipped with an external electric oven was packed with 5 ml of apalladium catalyst (supplied by Nikki Kagaku K.K.) comprising 0.5% byweight of palladium supported on active carbon, The catalyst-packedreaction tube was heated to 150° C. The heated reaction tube waspre-treated with hydrogen by flowing hydrogen gas through the tube at arate of 200 ml/min for a hours. Thereafter1-chloro-2,3,3,4,4,5,5-heptafluoro-cyclopentene was supplied at a rateof 0.1 ml/min to a vaporizer maintained at 100° C., and thehydrogenation was carried out for 20 hours. The thus-produced gaseousmixture was washed with water, and dried with calcium chloride, and thencollected in a glass trap cooled to −78° C. Analysis of the collectedproduct by gas chromatography revealed that the conversion of; the rawmaterial was 99%, and the contents of1,1,2,2,3,3,4-heptafluorocyclopentene,1,3,3,4,4,5,5-heptafluorocyclopentene and1,1,2,2,3,3-hexafluorocyclopentane were 89%, 4% and 6%, respectively.

EXAMPLE 7

Preparation of Catalyst

An SUS 316 reaction tube having a diameter of 2.54 cm and a length of 40cm was packed with 50 ml of a palladium catalyst (supplied by NikkiKagaku K.K.; average particle diameter 3 mm) comprising 0.5% by weightof palladium supported on alumina spheres. Nitrogen gas was allowed toflow at a rate of 100 ml/min through the reaction tube while it washeated to 250° C. The heated reaction tube was dried for two hours, andthen the temperature was further elevated to 300° C., and hydrogenfluoride gas was supplied to the tube at a rate of 400 ml/min, When itwas observed that the generation of water ceased, the supply of hydrogenfluoride was stopped. Then nitrogen gas was allowed to flow at a rate of50 ml/min to remove the surplus hydrogen fluoride.

Vapor Phase Fluorination of Chlorofluoroalkene

An SUS 316 reaction tube having a diameter of ½ inch and a length of 15cm was packed with 5 ml of the catalyst prepared above in the samemanner as mentioned in Example 5. The catalyst-packed reaction tube waspre-treated with hydrogen by flowing hydrogen gas through the tube at arate of 200 ml/min for 10 hours. Thereafter1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene was supplied at a rate of0.1 ml/min to a vaporizer maintained at 100° C. and the hydrogenationwas carried out for 20 hours. The thus-produced gaseous mixture waswashed with water, and dried with calcium chloride, and then collectedin a glass trap cooled to −78° C. Analysis of the collected product bygas chromatography revealed that the conversion of the raw material was99%, and the contents of 1,1,2,2,3,3,4-heptafluorocyclopentene,1,3,3,4,4,5,5-heptafluorocyclopentene and1,1,2,2,3,3-hexafluorocyclopentane were 92%, 6.3%, and 0.7%,respectively.

Industrial Application

According to the present invention, the compound having at least 4carbon atoms of formula (3) can be produced industrially advantageouslyat a high purity from the compound having at least 4 carbon atoms fromof formula (1).

The produced compound having at least 4 carbon atoms of formula (3) doesnot destroy of the ozone-layer, and therefore, has a wide use includinga detergent and a solvent as an alternative for freon.

What is claimed is:
 1. A process for preparing a compound having at least 4 carbon atoms and represented by the following formula (3), characterized in that a compound having at least 4 carbon atoms and represented by the following formula (1) is hydrogenated in the presence of a noble metal catalyst in the liquid phase or the vapor phase: R¹—C¹Cl═C²F—R²  (1) wherein C¹ and C² designate two carbon atoms of the compound; and wherein R¹ is an alkyl group having 1 to 8 carbon atoms which may be fluorinated, and R² is an alkyl group having 1 to 8 carbon atoms which may be fluorinated, and R¹ and R² may form together a divalent hydrocarbon group having 2 to 8 carbon atoms represented by the formula —R¹—R²—, in which the entirety or a part of the hydrogen atoms in the hydrocarbon group of formula —R¹—R²— may be fluorinated, and which forms together with C¹ and C² an alicyclic compound; R¹—C¹H₂—C²HF—R²  (3).
 2. The preparation process according to claim 1, wherein the compound a having at least 4 carbon atoms, represented by formula (1), is an alicyclic compound having 4 to 10 carbon atoms in the cyclic structure.
 3. The preparation process according to claim 1, wherein the compound having at least 4 carbon atoms and represented by formula (1) is 1-chloro-2,3,3,4,4,5,5-heptafluorocyclopentene.
 4. The preparation process according to claim 1, wherein the noble metal catalyst is used in a form supported on a carrier; the amount of the catalyst supported is in the range of 0.05 to 20% by weight based on the carrier.
 5. The preparation process according to claim 1, wherein the noble metal catalyst comprises at least one metal selected from palladium, rhodium and ruthenium.
 6. The preparation process according to claim 1, wherein at least two mols of hydrogen, per mol of the compound of formula (1), is used for the hydrogenation.
 7. The preparation process according to claim 1, wherein the hydrogenation is carried out at a reaction temperature in the range of room temperature to 350° C. and a reaction pressure in the range of normal pressure to 50 kgf/cm².
 8. The preparation process according to claim 1, wherein the hydrogenation is carried out in the vapor phase.
 9. The preparation process according to claim 1, wherein the compound of the formula (1) is prepared by allowing a compound having at least 4 carbon atoms and represented by the following formula (4): R¹C¹Cl═C²Cl—R²  (4) wherein C¹ and C² designate two carbon atoms of the compound; and R¹ and R² are the same as R¹ and R² in the formula (1), respectively, to react with a fluorinating agent.
 10. The preparation process according to claim 9, wherein the reaction of the compound of formula (4) having at least 4 carbon atoms with the fluorinating agent to give the compound of formula (1) having at least 4 carbon atoms is carried out in a reaction vessel equipped with a distillation column while a reaction product is continuously withdrawn from the reaction system.
 11. The preparation process according to claim 9, wherein the fluorinating agent is used in an amount of 0.5 to 2 mols per mol of the compound of formula (4) having at least 4 carbon atoms.
 12. The preparation process according to claim 9, wherein the fluorinating agent is potassium fluoride.
 13. The preparation process according to claim 9, wherein the fluorinating reaction is carried out in an aprotic polar solvent or a mixed solvent comprising an aprotic polar solvent and an aromatic hydrocarbon.
 14. The preparation process according to claim 13, wherein the aprotic polar solvents are N,N-dimethylformamide and the aromatic hydrocarbon is at least one selected from benzene, toluene and xylene. 